We found this circuit in a magazine 73 from the 90's. It is a circuit indicated for radio-amateur transmitters with the frequencies determined by the sets of coils.
This circuit is from 2001 documentation, serving to multiplex stereo signals for FM transmitters. The...
This circuit reverses the signal if both positive and negative. We found it in an American...
Found in a publication by Gernsback from 1960, this circuit makes use of germanium transistors of the time....